Lactose intolerance

Lactose intolerance is a condition wherein an individual cannot digest lactose, a sugar found in milk. When a lactose intolerant individual ingests product which has lactose in it, he or she may experience extreme stomach discomfort as well as other symptoms such as cramping and bloating. Such individuals do not produce an enzyme called lactase that breaks down lactose after weaning.[1]

Lactose intolerance is an inherited inability to properly digest dairy products, due to a deficiency in the amount of the enzyme, β-galactosidase in the small intestine. This enzyme is necessary for the hydrolysis of lactose (a disaccharide) into its constituent monosaccharides, glucose and galactose. Symptoms of lactose intolerance, including abdominal cramps, flatulence and frothy diarrhea, can increase with age.[2]

Cheese making process destroy lactose from the cheese and mature cheeses are thus lactose free.[3]

The proportion of lactose intolerant individuals varies by region on the planet. 99% of Chinese are lactose intolerant, whereas only 10% of Americans are. Recent research indicates that lactose intolerance is high where cows were not domesticated.[4] At higher latitudes, lactose intolerance decreases. As average temperature increases, lactose intolerance increases.[5]

Lactose tolerance is determined by a recessivegene. Researchers have recently identified a DNAmutation that allows people to tolerate milk.[6] Lactose tolerance is often called lactose persistence.